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|
-- | Source errors
module GHC.Types.SourceError
( SourceError (..)
, mkSrcErr
, srcErrorMessages
, throwErrors
, throwOneError
, handleSourceError
)
where
import GHC.Prelude
import GHC.Types.Error
import GHC.Utils.Monad
import GHC.Utils.Panic
import GHC.Utils.Exception
import GHC.Utils.Error (pprMsgEnvelopeBagWithLocDefault)
import GHC.Utils.Outputable
import GHC.Driver.Errors.Ppr () -- instance Diagnostic GhcMessage
import GHC.Driver.Errors.Types
import Control.Monad.Catch as MC (MonadCatch, catch)
mkSrcErr :: Messages GhcMessage -> SourceError
mkSrcErr = SourceError
srcErrorMessages :: SourceError -> Messages GhcMessage
srcErrorMessages (SourceError msgs) = msgs
throwErrors :: MonadIO io => Messages GhcMessage -> io a
throwErrors = liftIO . throwIO . mkSrcErr
throwOneError :: MonadIO io => MsgEnvelope GhcMessage -> io a
throwOneError = throwErrors . singleMessage
-- | A source error is an error that is caused by one or more errors in the
-- source code. A 'SourceError' is thrown by many functions in the
-- compilation pipeline. Inside GHC these errors are merely printed via
-- 'log_action', but API clients may treat them differently, for example,
-- insert them into a list box. If you want the default behaviour, use the
-- idiom:
--
-- > handleSourceError printExceptionAndWarnings $ do
-- > ... api calls that may fail ...
--
-- The 'SourceError's error messages can be accessed via 'srcErrorMessages'.
-- This list may be empty if the compiler failed due to @-Werror@
-- ('Opt_WarnIsError').
--
-- See 'printExceptionAndWarnings' for more information on what to take care
-- of when writing a custom error handler.
newtype SourceError = SourceError (Messages GhcMessage)
instance Show SourceError where
-- We implement 'Show' because it's required by the 'Exception' instance, but diagnostics
-- shouldn't be shown via the 'Show' typeclass, but rather rendered using the ppr functions.
-- This also explains why there is no 'Show' instance for a 'MsgEnvelope'.
show (SourceError msgs) =
renderWithContext defaultSDocContext
. vcat
. pprMsgEnvelopeBagWithLocDefault
. getMessages
$ msgs
instance Exception SourceError
-- | Perform the given action and call the exception handler if the action
-- throws a 'SourceError'. See 'SourceError' for more information.
handleSourceError :: (MonadCatch m) =>
(SourceError -> m a) -- ^ exception handler
-> m a -- ^ action to perform
-> m a
handleSourceError handler act =
MC.catch act (\(e :: SourceError) -> handler e)
|
